I can't tell you your answer, but I can tell you you're taking a poor quality vitamin. They're not created equal. This one uses cheap ingredients that are not well absorbed, such as iron oxide in the dye, and it includes dyes and fillers and binders that can be toxic. You'd do better with a better company. This one doesn't even use mixed tocopherols, just alpha -- didn't think anyone did that anymore. But the easy way to answer your question is to stop taking them and get tested again and see if the test is different. It's also true that if you had gotten tested the next day you might have come out normal -- only repeated tests over time can produce an accurate picture, as we change from day to day and hour to hour. What is also possible that this supplement, or, given you don't seem to be as particular about what you ingest as some, you might be eating some other food or taking an herb that is tainted. But again, whenever you suspect a supplement is a problem, stop taking it and see if it solves the problem.